1. Field of the Invention
This invention relates to an image formation apparatus of the liquid development type, and more particularly to such an image formation apparatus in which the wait time preceding the starting of the process is controlled in accordance with the time during which the apparatus was left inoperative (hereinafter referred to as the downtime).
2. Description of the Prior Art
Generally, the liquid developer used for the electrophotography of the transfer type has the property of being fixed when it is dried, and the developer deposited on a photosensitive drum or like object to be developed is dried and fixed to the surface of the drum or the like if the drum or the like is left unused for a long time, so that it becomes difficult to clean the surface of such object to be developed and if cleaned, such surface may be injured during the cleaning thereof. To overcome these problems, there has been adopted a method of providing a predetermined time after the closing of the main switch but before the starting of the copying operation, for example, a time for the surface of the drum or the like to be wet, namely, a wait time. According to this method, a predetermined wait time is required each time the main switch is closed, independently of the surface condition of the drum, and this means a loss of time which is disadvantageous in practice.
There is also known a method of detecting the length of the downtime from the discharging condition of a capacitor and reducing the wait time if the downtime is within one hour or so. This method, however, has the disadvantage that the downtime detectable to reduce the wait time is limited to a short length because of the property of the capacitor.
There is a further problem that the mark imparted to the drum surface by a blade for cleaning the drum surface to make the drum available for repeated use becomes more and more difficult to remove as the downtime is longer, but there is no wait time setting system which has covered such problem.
Also, toner particles in the liquid developer used for electrophotography precipitate with time if the apparatus is left unused, so that the transmittance of the developing liquid becomes thinner with time. Therefore, if copying is effected after a long downtime, there will only be obtained a thin copy image. Consequently, it is not preferable to reduce the wait time in order simply to decrease the loss of time.